Systems and methods for automated control of mixing and aeration in treatment processes

ABSTRACT

A system and method for automatically controlling aeration and mixing processes are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.16/239,207, filed Jan. 3, 2019, which is a continuation of U.S. patentapplication Ser. No. 15/429,986, filed Feb. 10, 2017, which is acontinuation of U.S. patent application Ser. No. 14/147,209, filed onJan. 3, 2014, now U.S. Pat. No. 9,567,245, issued Feb. 14, 2017, whichis a continuation of U.S. patent application Ser. No. 13/591,509 filedon Aug. 22, 2012, of which is a continuation of U.S. patent applicationSer. No. 13/252,905 filed on Oct. 4, 2011, now U.S. Pat. No. 8,323,498,issued Dec. 4, 2012, which claims priority to U.S. Provisional PatentApplication Ser. No. 61/389,645, filed on Oct. 4, 2010, the contents ofwhich are incorporated herein in their entireties.

FIELD OF THE INVENTION

The present invention relates to control systems, particularly systemsand methods for automatically controlling mixing and aeration processes,such as in wastewater treatment.

BACKGROUND

Methods and systems for treating wastewater are known in the art. Suchmethods may include aerobic, anoxic, and anaerobic processes.

SUMMARY OF THE INVENTION

The present invention includes a system for automatically controlling antreatment process based upon at least one or more dynamically measuredparameters including a probe for measuring at least one parameter of asubstance, a control panel in communication with the probe wherein thecontrol panel receives data from the probe representing the measurementof the at least one parameter, a programmable logic controller incommunication with the control panel, and an aerator in communicationwith the control panel. The system is configured to activate the aeratorupon measurement of a first parameter characteristic of adynamically-measured parameter and to deactivate the aerator uponmeasurement of a second parameter characteristic of adynamically-measured parameter.

The present invention further includes a method for controlling theaeration of a substance based upon dynamically-measured data. The methodincludes measuring at least one parameter of the substance, activatingaeration of the substance upon measurement of a first characteristic ofthe at least one parameter, and deactivating aeration of the substanceupon measurement of a second characteristic of the at least oneparameter.

The present invention further includes a method for controlling theaeration of a substance based upon dynamically-measured data. The methoddynamically measuring and monitoring an ORP value, nitrateconcentration, and ammonia concentration of wastewater. The method alsoincludes activating aeration of the wastewater upon the detection ofeither an ORP nitrate knee, a minimum ORP threshold value, or a maximumammonia threshold concentration and deactivating aeration of thewastewater upon the detection of either a maximum nitrate thresholdconcentration or a maximum ORP value.

In addition, the present invention includes a method for thesimultaneous nitrification and denitrification of wastewater. The methodincludes dynamically measuring and monitoring a dissolved oxygenconcentration, a nitrate concentration, and an ammonia concentration ofthe wastewater, aerating the wastewater, adjusting the aeration suchthat the dissolved oxygen concentration is maintained in a range fromabout 0.25 mg/L to about 1.0 mg/L, the nitrate concentration ismaintained in a range from about 0 mg/L to about 30 mg/L, and theammonia concentration is maintained in a range from about 0 mg/L toabout 30 mg/L. The method further includes mixing the wastewater.

The present invention may be better understood by reference to thedescription and figures that follow. It is to be understood that theinvention is not limited in its application to the specific details asset forth in the following description and figures. The invention iscapable of other embodiments and of being practiced or carried out invarious ways.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention are better understood when the following detailed descriptionis read with reference to the accompanying drawings, wherein:

FIG. 1 is a side cut-away view of a basin with aeration and mixingcomponents for use in conjunction with an embodiment of the presentinvention;

FIG. 2 is a schematic diagram of a system that depicts an embodiment ofthe present invention;

FIG. 3 is a graphical representation of the operation of an embodimentof a system of the present invention based upon measured wastewaterparameters;

FIG. 4 is a flowchart that illustrates the logic of one embodiment ofthe present invention;

FIG. 5 is a flowchart that illustrates the logic of an alternativeembodiment of the present invention;

FIG. 6 is a schematic diagram of a system that depicts an alternativeembodiment of the present invention.

FIG. 7 is a flowchart that illustrates the logic of another embodimentof the present invention; and

FIG. 8 is a flow chart that illustrates the logic of another alternativeembodiment of the present invention.

Repeat use of reference characters in the present specification anddrawings is intended to represent same or analogous features or elementsof the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent file or records, but otherwise reserves all copyrightrights whatsoever.

Reference will now be made in detail to various embodiments of theinvention, one or more examples of which are illustrated in theaccompanying drawings. Each example is provided by way of explanation,not limitation, of the invention. In fact, it will be apparent to thoseskilled in the art that modifications and variations can be made in thepresent invention without departing from the scope and spirit thereof.For instance, features illustrated or described as part of oneembodiment may be used on another embodiment to yield a still furtherembodiment. Thus, it is intended that the present invention covers suchmodifications and variations as come within the scope of the appendedclaims and their equivalents.

Various processes often require multiple phases, and it may beadvantageous to monitor the parameters during such processes andautomatically change operating conditions based upon observed parametersof the process. By way of example, the treatment of wastewater mayinvolve various treatment phases, such as aerobic, anaerobic, and anoxictreatment phases, and it may be useful to measure parameters of thewastewater and to automatically initiate changes between treatmentphases based upon the measured parameters, which may indicate thetreatment requirements of the wastewater.

FIG. 1 provides a cut-away side view of basin 2, which is one embodimentof a containment unit for wastewater that can be used with the presentinvention. Basin 2 is shown with four sidewalls 4 and bottom 6, whichmay be constructed of concrete in some embodiments. One of ordinaryskill in the art will appreciate that alternative types of containmentunits, such as tanks, vessels, channels, and ditches, are also withinthe scope of the present invention. The containment unit mayadditionally have an inlet through which wastewater enters and an outletthrough which the treated wastewater exits. In some embodiments, thecontainment unit may allow for continuous flow of the wastewater whereasother embodiments may restrict the flow of the wastewater. In someembodiments, multiple containment units, of the same type or ofdiffering types, may be present and connected such that the wastewaterpasses through them sequentially or not connected such that wastewaterpasses thru them in parallel.

As shown in FIG. 1, a mixing system for use with basin 2 includescontroller box 12, supply headers 18, first lines 22, second lines 22,and nozzles 30, wherein each first line 22 is connected to a second line22 by way of a T-type connector 23. The operation of the mixing systemand additional components thereof are described in detail in U.S. patentapplication Ser. No. 12/577,529, which is incorporated herein in itsentirety by reference thereto. It will be readily apparent to one ofordinary skill in the art that alternative mixing systems, such asmechanical mixers, submersible mixers, surface mixers, agitators, staticmixers, and hyperbolic mixers, can be used with basin 2 or anycontainment unit for wastewater and are within the scope of the presentinvention. Similarly, the number of mixing components and layout of themixing components may vary within the scope of the present invention. Inaddition, the number and arrangement of mixing components may vary inother embodiments of the present invention.

Basin 2 is also equipped with an aeration system. As shown in FIG. 1, anembodiment of an aeration system includes diffuser heads 100 as theaerators, and each diffuser head 100 is serially connected to diffuserpipe 102. Each depicted diffuser pipe 102 is then connected with headerpipe 104, and header pipe 104 is connected with supply pipe 106. Supplypipe 106 is connected to blower 108, which delivers air under pressureto each diffuser head 100 by way of supply pipe 106, header 104, anddiffuser pipe 102. Valve 109 is connected with blower 108 to control theflow of air to supply pipe 106. In some embodiments, diffuser heads 100may be located in proximity to bottom 6 but are not flush with bottom 6.In addition, diffuser pipe 102 may be secured to bottom 6 or locatedabove bottom 6 and supply pipe 106 may be secured to a side 4 of basin2.

The depicted aeration system and components thereof are illustrativeonly, and it will be readily apparent to one of ordinary skill in theart that alternative types of aeration systems, aerators, and aerationcomponents are within the scope of the present invention. By way ofexample, alternative aerators for use in embodiments of the presentinvention may include fine bubble (or fine pore) diffusers or coursebubble diffusers, mechanical aerators, centrifugal blowers, jetaerators, and positive displacement blowers. In addition, the layout andnumber of aeration devices may vary in alternative embodiments of thepresent invention. For instance, in some embodiments, the number orarrangement of diffuser heads 100 may vary.

Probes for measuring various parameters may also be located within basin2. Some probes may directly detect a certain parameter or certainparameters whereas other probes may detect or measure a parameter orparameters that can then be used to compute a desired parameter, eitheralone or in combination with other data. As used herein, the term“measured” includes detected parameters, directly-measured values ofparameters, and parameter values calculated or otherwise determined fromthe direct measurement or detection of one or more other parameters,either alone or in combination with additional data or measurements.

As shown in basin 2, such probes may include Oxygen-Reduction Potential(ORP) probe 108, nitrate (NO₃—N) probe 110, ammonia (NH₃—N) probe 112,dissolved oxygen (DO) probe 114, and pH probe 124. In some embodiments,a probe may actually measure ammonium concentrations in order todetermine ammonia concentrations. In other embodiments, additionalprobes for measuring other parameters such as nitrite and/or temperaturemay be present, and in other embodiments some or all of the depictedprobes may be omitted. In yet other embodiments, multiple probes formeasuring a single parameter may be present, such as two or more DOprobes 114. In some embodiments, a system may include multiple basins.In those embodiments, probes may be located in each basin or,alternatively, probes may be placed in a single basin and themeasurements from those probes may be used to control the processes ineach basin. In an even further embodiment, each basin may include one ormore DO probes such that the DO level can be controlled independentlyfor each basin, but the remaining processes may be monitored andcontrolled for all basins by using probes in a single basin. In someembodiments of the present invention, the probes may measure the desiredparameters without any need for sampling the substance. In this manner,in some embodiments, the probes may be in direct and constant contactwith the substance for which parameters are being measured.

FIG. 2 depicts system 200, which is one embodiment of a system of thepresent invention. As shown in system 200, ORP probe 108 is incommunication with ORP probe processor 109, nitrate probe 110 is incommunication with nitrate probe processor 111, ammonia probe 112 is incommunication with ammonia probe processor 113, DO probe 114 is incommunication with DO probe processor 115, and pH probe 124 is incommunication with pH probe processor 125. Probe processors may besupplied with a probe from the probe manufacturer. As used herein, thereference “in communication with” indicates that data and/or signals aretransferrable between the referenced components, and include bothphysical connections and wireless connections. In addition, “incommunication with” also includes embodiments in which the referencedcomponents are in direct connection (i.e., directly connected to eachother with a cable) as well as indirect connections, such as when datais transmitted through an intermediate component and either relayed inthe same format or converted and then relayed to the referencedcomponent. In other embodiments, some or all of ORP probe 108, nitrateprobe 110, ammonia probe 112, DO probe 114, and pH probe 124 may be incommunication with a single probe processor.

As shown in system 200, a programmable logic controller (PLC) 116 is incommunication with and receives input from ORP probe processor 109,nitrate probe processor 111, ammonia probe processor 113, DO probeprocessor 115, and pH probe processor 125. PLC 116 is also incommunication with control panel 118. Control panel 118 may contain aPC, a PLC, a device to aid the communication between the PC and PLC, andother wiring and miscellaneous hardware. In some embodiments, PLC 116and control panel 118 may be combined within a single device. Forinstance, in some embodiments, control panel 118 may include a PLC and aseparate PLC 116 may not be required. In other embodiments, more thanone PLC 116 may be present. In other alternative embodiments, a probeprocessor may be omitted for some or all probes and probes may be indirect communication with PLC 116 without a probe processor.

In some embodiments, basin 2 may contain wastewater requiring treatment.Influent wastewater often contains ammonia (NH₃—N) or other organicwaste that includes nitrogen. In many wastewater treatment processes, anaerobic process is used to treat the waste using dissolved oxygen alongwith bacteria to convert the ammonia to nitrate (NO₃—N), a process thatmay be referenced as nitrification. After the ammonia has been convertedto nitrate, an anoxic process is often performed to convert the nitrateto nitrogen gas, called denitrification. During this anoxic process,dissolved oxygen is not provided to the wastewater undergoing treatmentand the bacteria rely upon oxygen from the nitrate, which results in thenitrate to nitrogen gas conversion. Therefore, it may be desirable toautomatically convert between the aerobic and anoxic treatment processesby controlling the flow of oxygen or other gas to the wastewater. Inaddition, it may be beneficial to convert between those treatmentprocesses based upon the levels of certain parameters in the wastewater.

In operation, control panel 118 and PLC 116 may control the flow of airto diffuser heads 100 based upon parameters dynamically measured fromthe wastewater using one or more of ORP probe 108, nitrate probe 110,ammonia probe 112, DO probe 114, pH probe 124, or otherparameter-specific probes. For instance, with reference to FIG. 2, insome embodiments, control panel 118 and PLC 116 may activate anddeactivate the flow of air to diffuser heads 100, thereby controllingthe aeration of the contents of basin 2. In other embodiments, controlpanel 118 and PLC 116 may also control the rate of air flow to diffuserheads 100 to control the aerobic phase. As explained further herein,this system and process allow for automated control between aerobic andanoxic wastewater treatment processes based upon dynamically-measuredparameters of the wastewater. In other embodiments, in addition toaeration control, control panel 118 may control the activation anddeactivation of the mixing system as well as the speed or mixing rate.The entire operation of system 200 is described in detail below.

In operation, with reference to FIG. 2, Oxygen-Reduction Potential (ORP)probe 108, nitrate (NO₃—N) probe 110, ammonia (NH₃—N) probe 112,dissolved oxygen (DO) probe 114, and pH probe 124 dynamically measurethe parameter of the respective probe and transmit the measurements toORP probe processor 109, nitrate probe processor 111, ammonia probeprocessor 113, DO probe processor 115, and pH probe processor 125respectively. That information is then transmitted from the respectiveprobe processors to PLC 116, and PLC 116 then converts the data andtransmits the converted information to control panel 118.

FIG. 3 provides a graphical illustration of measured parameters that aretransmitted to control panel 118 over a time period. At the beginning ofthe depicted time period, the wastewater system is in the latter stagesof an anoxic treatment in which the aerators are not activated and thedissolved oxygen levels are at or near zero. By monitoring the measuredparameters of the wastewater undergoing treatment, system 200 cancontrol when to activate air flow to diffuser heads 100, thereby endingthe anoxic treatment process and beginning the aerobic treatmentprocess, such as when the nitrate in the wastewater is depleted.

By way of example, one manner of detecting when to end the anoxictreatment process and begin the aerobic treatment process by activatingthe flow of air to the aerators, such as diffuser heads 100, is bymonitoring the measured ORP level. ORP is a value that represents theratio of oxidants to reductants in the subject system, such as thewastewater in the illustrative embodiment. Because the ratio isrepresented as oxidants to reductants, the ORP value decreases as oxygenis removed from the system in the anoxic process and as nitrate isconverted to nitrogen gas. During anoxic treatment processes,characteristic indications in the ORP values may be observed. Forinstance, one such characteristic value is the ORP nitrate knee, whichis shown at the beginning of range E in FIG. 3. The ORP nitrate knee isnot detected as a specific value but instead as a slope changeindicating this characteristic point as a first order derivation. TheORP nitrate knee indicates that the system is nearing conversion to ananaerobic state, and the ORP nitrate knee may further indicate that thenitrate level in the system is nearing depletion as shown in FIG. 3. Ifthe system is allowed to become anaerobic, then difficulties may beencountered in returning the system to an aerobic or anoxic state withthe necessary healthy bacteria.

In one embodiment, the ORP nitrate knee may be determined by performingleast squares linear regression on data points of two series. A firstdata series may include data from recently measured data points over afirst time period, and a second data series may include data measuredover a time period preceding the first time period. The least squareslinear regression calculation of the first data series is thensubtracted from the least squares linear regression calculation of thesecond data series and if the difference exceeds a predetermined value,then the ORP nitrate knee is detected. As the calculation isprogressively run, the measured data points are continually orperiodically measured for the calculation. One illustrative embodimentof detecting the ORP nitrate knee is set forth in the software programcode appended hereto as Chart A.

Upon detection of the ORP nitrate knee by control panel 118, controlpanel 118 sends signals to PLC controller 116 and, as a result, PLCsends signals to valve actuator 120, which controls valve 109. As aresult, valve 109 is actuated and permits blower 108 to provide air todiffuser heads 100 by way of supply pipe 106, header pipe 104, anddiffuser pipe 102. Other types of aeration equipment may be started by adifferent method, such as an electric starter, activated by the PLCsignal. As a result, oxygen is provided to the wastewater undergoingtreatment and an aerobic treatment process is commenced. Therefore, asshown on FIG. 3, the air is turned on at the beginning of range A as aresult of monitoring the ORP measurements and, particularly, by the ORPnitrate knee serving as the trigger for activation of the aerobictreatment process. Although the ORP nitrate knee is detected at thebeginning of range E in FIG. 3, the delay in activating the air flow tothe wastewater until the end of range E is a result of the lag indetecting the ORP nitrate knee, processing the data, and activating thecomponents. The lag time represented by range E can vary in differentsystems, but because the ORP nitrate knee indicates that the system isnearing conversion to an anaerobic state, it may be beneficial to limitthe duration of the lag time represented by range E. Given the historyof data that may be stored in the control panel over time and at similarpoints in the cycle, the point of change can be anticipated by thesystem enabling more precise control.

In this regard, using the ORP nitrate knee as a trigger for commencingthe aerobic treatment process may be useful because it permits lag timebefore the system becomes anaerobic. In addition, ORP measurementsindicate relative values and do not have a minimum value of zero.Therefore, as opposed to using other values as an indication foractivating a treatment process, such as concentration levels ofcomponents for which precision may be decreased as the concentrationlevels decrease, ORP levels can be constantly measured with precision.In addition, ORP probes may be more reliable for use in certainembodiments than other types of probes.

In alternative embodiments of the present invention, other parameterscan be monitored, either in addition to the ORP nitrate knee or insteadof the ORP nitrate knee, to activate an aeration treatment process. Forinstance, in one embodiment, the nitrate value itself can be used as atrigger to activate the aerobic treatment process and the flow of airmay be commenced as described above when the nitrate level is depletedor near depletion. In other embodiments, the nitrate level may serve asa secondary (or back-up) value for activating the aerators. Forinstance, if the nitrate level of wastewater approaches zero before theORP nitrate knee were detected, then the aerators may be activated. Insome embodiments, having one or more secondary values for triggeringresponses is desirable because it will maintain the proper systemfunctionality in the event that a probe for another parameter is damagedor malfunctioning. In yet another embodiment, a maximum ammonia levelmay be used as a trigger to initiate the aerobic treatment process, suchas an ammonia level of about 7.0 mg/L could be used in FIG. 3 as such atrigger. In yet another embodiment, the ORP value falling below a setlevel, such as below −50 mV, may be a trigger to initiate the aerobictreatment process. In a further embodiment, the pH measurement can beused as a trigger to initiate the aerobic process. For instance, aplateau in the pH measurements may occur when dentrification is completeor nearly complete. Upon detection of such a pH plateau, someembodiments may trigger aeration. In addition, in other embodimentsvalues of pH may be used to activate, deactivate, or control aeration oraeration rate. Regardless of the parameter or parameters used, controlpanel 118 and PLC 116 operate to activate the aeration as describedabove upon the triggering parameter's detection.

In addition to activating the flow of oxygen to the wastewater tocommence an aerobic treatment process as explained above, embodiments ofthe present invention may also be used to regulate treatment parametersbased upon dynamic measurements of the parameters. For instance, in someembodiments, it may be desirable to maintain the DO level in thewastewater at or within a certain level during an aerobic treatmentprocesses and exceeding that level may not be beneficial. Therefore, insome embodiments, the flow of oxygen to the wastewater may be activatedor controlled in order to maintain the DO concentration at the desiredand optimal level.

By way of example, in some embodiments, the desired DO level during anaerobic treatment process may be 2.0 mg/L, and the flow of oxygen may becontinually turned off and on or the oxygen flow rate increased orreduced to maintain the DO level at this value during the aerobictreatment process. Although in some embodiments the flow of oxygen iscontrolled, other embodiments may control the flow of other gases, suchas atmospheric air. For instance, at the beginning of the aerobictreatment process shown in FIG. 3, the flow of oxygen to the wastewateris provided at a maximum flow rate during range A. This initialprovision of oxygen serves to quickly raise the DO level in the system.However, as indicated, it may not be beneficial to exceed a threshold DOlevel, such as 2.0 mg/L. Therefore, control panel 118 may transmitsignals to control the flow of air to the wastewater through theaerators based upon real-time, dynamic measurements of the DO level asmeasured by DO probe 114. In response to the DO level nearing orexceeding a threshold level, control panel 118 may send a signal to PLC116, and PLC 116 may signal valve actuator 122 to restrict or stop theoxygen flow to diffuser heads 100. After oxygen flow is reduced orterminated and the DO level depletes near or below the optimal level,then control panel 118, via the same mechanism, may reactivate orincrease the oxygen flow to maintain or return the DO level to thethreshold level. In other embodiments, other DO concentration levels maybe desirable. By way of example, a DO level within the range within therange of 0.5 to 2.0 mg/L may be desirable in some embodiments. In otherembodiments, the desirable range may be 0.25 to 0.75 mg/L, 1.0 to 1.5mg/L, or 0.25 to 2.0 mg/L. In some embodiments, the oxygen flow may becontrolled using historical data of valve position for a given DOconcentration.

In some embodiments, such as mechanical aerators or blowers withoutvariable speed drives that can only be turned on or off and the oxygenflow not regulated, control panel 118 may signal to deactivate less thanall of a plurality of devices used to compress atmospheric air forpurposes of oxygenation, such as, without limitation, positivedisplacement blowers, centrifugal blowers, or rotary disc surfaceaerators, in order to decrease the overall oxygen flow to the wastewaterwithout regulating the specific output of each blower. As a result ofsuch optimization levels as well as consumption of oxygen by bacteria,the DO level during the aerobic treatment process shown in FIG. 3 is notconstant but fluctuates around 2.0 mg/L, as referenced as the DOOptimization in range B. In other embodiments, the system may maintain amore constant DO level at or near a desired threshold during aerobictreatment processes.

In other embodiments, the oxygen requirements fluctuate based upon theammonia level in the system with which the oxygen reacts. In suchembodiments, the flow of air to the wastewater may be controlled as setforth above based upon the measured ammonia level, wherein oxygen flowis increased for high ammonia levels and decreased for lower ammonialevels. For other measurable wastewater parameters such as TSS, COD orBOD, the flow of air to the wastewater may also be controlled.

As explained above, oxygen (as used in the following example) or othergas, such as atmospheric air, is provided through diffuser heads 100during range A and range B in FIG. 3 as the aerobic treatment process isunderway. Similar to the termination of the anoxic treatment processdescribed above, parameters of the wastewater may be dynamicallymeasured and monitored during the aerobic treatment process so that theprocess can be automatically terminated. In one embodiment of thepresent invention, one trigger for terminating oxygen flow to thewastewater may be the measured nitrate level. For instance, as shown inFIG. 3, the aerators are deactivated when the nitrate level reaches aset concentration, such as 6 mg/L and, upon such termination, anotheranoxic treatment process is commenced to reduce the nitrate level thathas risen during the aerobic treatment process. In other embodiments, analternative nitrate threshold may be used depending upon a particularsystem's requirements and operations, such as a threshold within therange of about 2.0 to 15.0 mg/L, including a threshold in alternativeembodiments, for instance, such as 2 mg/L, 3 mg/L, 4 mg/L, 5 mg/L, 6mg/L, 7 mg/L, 8 mg/L, 9 mg/L, 10 mg/L, 11 mg/L, 12 mg/L, 13 mg/L, 14mg/L, or 15 mg/L. In other embodiments, the threshold may be within arange of about 2.0 to 6.0 mg/L, including a threshold of about 2 mg/L, 3mg/L, 4 mg/L, 5 mg/L, 6 mg/L, or 7 mg/L. As indicated in FIG. 3, themeasured nitrate level may experience a more gradual variation duringthe treatment processes than other parameters, thereby making it auseful parameter to trigger deactivation of the oxygen flow. Upondetection of a triggering parameter, such as the nitrate level reachinga threshold, control panel 118 sends a signal to PLC 116, and PLCsignals valve actuator 122 to close valve 109 to stop the oxygen flow,thereby ending the anaerobic or anoxic treatment process and commencingan aerobic treatment process.

In an alternative embodiment, the DO level may be used as a trigger,either as a primary or secondary trigger, for terminating the aerobictreatment process. For instance, if the measured DO level is maintainedover a certain level for a preset duration, thereby indicating that theoxygen is not being utilized to convert ammonia to nitrate, then theoxygen flow may be deactivated. In other embodiments, the ORP value canbe utilized as a trigger for deactivating the aerators. In someembodiments, the aerators may be deactivated when the ORP value reaches150 mV. Similarly, if an ORP value remains within a certain range for apredetermined duration, then some embodiments may terminate aeration.

Similarly, the measured ammonia level may be used as a trigger forterminating the aerobic treatment process. For instance, as shown inFIG. 3 at point C, the measured ammonia level is nearly depleted (havingbeen converted to nitrate as indicated by the increased nitrateconcentration at point C). Because the ammonia level is nearly depleted,an embodiment using this parameter as a trigger would stop the flow ofoxygen, thereby activating another anoxic cycle. If an embodiment usesthe ammonia level as a trigger for terminating the aerobic treatmentprocess, then a threshold can be set, such as absolute ammonia depletionor a range within absolute depletion, such as within 0.5 mg/L.

In other embodiments, other parameters may be used to terminate andinitiate treatment processes, either in lieu of or in addition to theparameters discussed above. For instance, in one alternative embodiment,the pH value may be monitored and thresholds may be set for turning onthe aeration process as described above and also for turning off theaeration process. For instance, a system that is fully nitrified mayhave a low pH that can be used as a trigger to end the anoxic process,such as about 6.2. Similarly, the wastewater pH will rise as the aerobicprocess is conducted and a maximum pH threshold can be set to end theaerobic treatment process, such as about 7.4. In other embodiments, avalley indicated in the pH measurements may indicate to terminate anaeration process. This pH valley is the opposite of a pH plateau thatmay be used to initiate aeration in some embodiments. In someembodiments in which additional parameters are measured, additional oralternative probes may be required than those disclosed in FIG. 1. Inother embodiments, the measured level of suspended solids in thewastewater may be used to control the mixing or aeration of thewastewater.

In some embodiments of the present invention, activating or and/ordeactivating the flow of oxygen to the wastewater may be based upon acombination of one or more parameters. For instance, in one embodiment,oxygen flow may be activated based upon a consideration of both the ORPnitrate knee and the measured nitrate level, wherein these respectivevalues are both considered. In some embodiments, each factor could beassigned a significance value, such as the ORP value being a morecontrolling factor than the nitrate level but both factors figuring intothe ultimate oxygen flow activation decision. FIGS. 4 and 5 illustratethe logic underlying example embodiments of the present invention,including the mixing function described in detail below. In addition,FIG. 6 illustrates an alternative embodiment that offers the samefunctionality but employs two PLCs 116. Other embodiments may employother additional PLCs 116. In some embodiments, one or both PLCsdepicted in FIG. 6 could be included within control panel 118. However,notably in some embodiments of the present invention, a measuredparameter is determinative to commence and/or end the aerobic or anoxictreatment process and the measured parameter does not merely trigger thestart of the running period of a set treatment time. Other embodimentsmay employ sets of probes with communications and PLCs dedicated toseparate tanks in parallel operating at various points in the cycle tocontrol each tank aeration or mixing simultaneously.

In some embodiments, as shown in FIG. 2, system 200 may also control themixing system. For instance, in some treatment processes, it isunnecessary to continuously mix the wastewater, and mixing may only beconducted during an anoxic treatment process. Therefore, in someembodiments of the present invention, control panel 118 may indicate toactivate or deactivate a mixing system as a function of whether aerationis occurring. In other embodiments, the necessity or rate of mixing maybe determined by monitoring the air flow during aeration to determine ifsupplemental mixing may be required to ensure the desired treatment.

With reference to FIGS. 1 and 2, controller 118 can send a signal to PLC116 indicating to activate or deactivate the mixing system, such as theflow of air to nozzle 30. In that instance, PLC 116 may transmit asignal to controller box 12, and controller box 12 would actuate controlvalves 14 based upon the signal to begin or end the mixing bycontrolling the supply of air to nozzle 30. In embodiments using othertypes of mixers, such as mechanical mixers, PLC 116 may transmit asignal to either supply or terminate power to the mixer.

In other embodiments of the present invention, multiple probes for asingle parameter (such as multiple ORP probes 108, nitrate probes 110,ammonia probes 112, DO probes 114, and pH probes 124) may be displacedwithin a containment unit, such as basin 2. Controller 118 may monitorthe differences between the measurements for a parameter at variousdisplacements within basin 2 and activate or deactivate mixing basedupon the concentration differentiation of a particular at various pointsof the wastewater undergoing treatment.

In alternative embodiments, control panel 118 can also transmit a signalto the mixing system to control the rate of mixing. For instance, in theembodiment depicted in FIG. 1, control panel 118 may send a signal toPLC 116, and PLC 116 may transmit a signal to controller box 12 toadjust the control valves, thereby controlling the mixing rate. Theactuator may control the flow rate by permitting or obstructing the flowof air, or the rate of air flow, to supply lines 18. In otherembodiments in which other types of mixers are used, such as mechanicalmixers, control panel 118 and PLC 116 may transmit signals to controlthe speed of the mixer. In still other embodiments, control panel 118and PLC 116 may send signals to deactivate some of a plurality ofmixers, thereby decreasing the overall mixing rate.

In addition to measured parameters, time parameters may be used tocontrol mixing or the flow of oxygen. For instance, a maximum period foran aerobic treatment process or an anoxic treatment process may be aparameter. In some embodiments, such time parameters could be determinedby control panel 118 based upon historical operation of the system,historical parameter measurements of the wastewater, and/or operatingconditions, such as flow rate of influent, weather conditions, and/ortime of day. The time parameters could serve either as a primary triggerfor starting and stopping the aerobic treatment process, either alone orin combination with other parameters, or alternatively as a secondary(back-up) parameter. In addition, in some embodiments, a flow meter maybe connected to diffuser pipe 102, header pipe 104, or supply pipe 106to measure the flow rate of oxygen, and the flow meter may be incommunication with PLC 116 and provide the measured data to controlpanel 118 for processing or to control the valve 109.

By way of example, FIG. 7 is a flow diagram of one embodiment of aprocess of the present invention. As illustrated, a system may beginoperation in an aerobic process, and aeration may continue until eitherthe detection of a maximum nitrate level, detection of a maximum ORPthreshold, or completion of an optional time period. In someembodiments, a default maximum nitrate level of about 4 mg/L may beused, and in other embodiments a maximum nitrate level up to about 30mg/L may be used, including all intermediary values from about 3 mg/L toabout 30 mg/L. In addition, some embodiments may use a default ORPmaximum level of about 300 mV. In addition, the aerators may cycle onand off or between high and low speeds during the aerobic cycle in orderto keep the DO concentration between predetermined levels. In oneembodiment, the DO concentration is maintained between about 0.5 mg/Land about 4.0 mg/L.

As further illustrated in FIG. 7, after aeration is terminated, mixingis initiated without aeration until either a minimum ORP threshold isdetected, an ORP knee is detected, a maximum ammonium value is detected,or an optional predetermined time period expires. By way of example, themaximum ammonia value in some embodiments may be from about 1 mg/L toabout 30 mg/L, including each increment in that range. In someembodiments, a minimum ORP threshold may be a value set below where anORP knee is detected, such that aeration is resumed in the event anexpected ORP knee is not detected. In even further embodiments,detection of an ORP knee may require that the ORP value be below apredetermined ORP value that is above the value at which an ORP knee isexpected to occur, such as ORP-2 in FIG. 8. Using this predeterminedORP-2 threshold value as a prerequisite for restarting aeration mayavoid false detections of an ORP knee.

In some embodiments using the exemplary process illustrated in FIGS. 7and 8, the optional time periods for stopping the aerobic and/or anoxicprocesses may be omitted as a triggering parameter. In some embodimentsin which one or more time periods are used as triggering parameters,such as the exemplary embodiment in FIG. 8, the optional time period maybe used as a secondary parameter and may be set to extend beyond theexpected duration of an ordinary cycle. Finally, in some embodiments ofthe present invention, the triggering parameters may be arranged in alogical hierarchy, as reflected in FIG. 8. In addition, the exemplarytime period pauses shown in FIG. 8 are optional, and in some embodimentsthose pauses may be omitted, shortened, or lengthened.

In another exemplary embodiment, nitrification and denitrification maybe performed simultaneously. By way of example, in some embodiments of asimultaneous nitrification and denitrification process of wastewater,the DO concentration of the wastewater is maintained at a low level,such as from about 0.25 to about 1.0 mg/L, and the wastewater issimultaneously mixed. The DO concentration may be maintained byfluctuating the flow of oxygen to the wastewater in response todynamically-measured parameters. In some embodiments, thedynamically-measured DO concentration in the system may be used toincrease or decrease the supply of DO to the system. In otherembodiments, the supply of DO to the system may be adjusted in responseto other dynamically-measured parameters. For example, the supply of DOto a system may be reduced if increased nitrate levels are detected, andthe supply of DO to the system may be increased if increased ammonialevels are detected. In one embodiment, the nitrate and/or ammonialevels may be maintained in the range from about 0 to about 30 mg/L, orat any intermittent values therein in alternative embodiments. In someembodiments, particular values within that range may be used to triggeran increase or decrease in the supply of DO to the system. In addition,dynamically-measured parameters may be used to control the mixingprocess as described herein.

In addition, control panel 118 may permit an operator to manuallycontrol the processes and system components, such as manually overridingthe automatic control and activating or deactivating aeration to thewastewater. In some embodiments, control panel 118 may include aninterface for inputting such manual instruction.

The requirements and operational preferences for a particular system mayvary based upon the facility or at various times for a particularfacility. In some embodiments of the present invention, systemrequirements and preferences, such as trigger points and particularoperational parameters, can be loaded into control panel 118. In someembodiments, the parameters may be based upon regulatory control orfacility discharge limits. In other embodiments, control panel 118 maybe in communication with another programmable logic controller orcomputer, either at the treatment facility or at another site, in whichthe operations parameters can be set and transmitted to control panel118. For instance, an existing facility may have existing PLCs orcontrol panels or hardware such as mixers and aerators, and the presentinvention could be interfaced with those existing systems, such as byloading software to perform the processes described herein andcommunicate with the previously-existing structures. In someembodiments, control panel 118 can be remotely accessible, such asthrough an internet interface. In this regard, control panel 118 may beconfigured to a network or internet connection.

In many systems, influent wastewater continually flows into the systemfor treatment, and the amount, flow rate, suspended solids level, andconcentration of the wastewater can vary based upon many factors. Forinstance, certain peak times such as morning and early evening mayproduce increased wastewater influence, whereas weather conditions suchas rain may dilute influent wastewater and require less mixing oraeration. Systems and processes of the present invention that commenceand terminate treatment processes based upon dynamically-measuredparameters of the system allow for treatment based upon the actual needof the system (such as the wastewater), as opposed to performingtreatments based upon preset time periods that do not necessarilyreflect the actual real-time treatment need of the wastewater. Thisdynamic monitoring and control may result in avoiding the mixing oroxygen flow being activated at unnecessary times or unnecessary rates,thereby saving mechanical wear and energy costs.

In addition, some embodiments of the present invention, and particularlycontrol panel 118, may track historical data of the measured parametersand treatment cycles. In addition, other values may be stored, such astemperature, time of day, rain volume, suspended solid concentration,and influent flow rate and volume. These parameters may then be used toperform predictive analysis for treatment cycles and to schedule oranticipate treatment cycles in a given system. In addition, this datamay be measured or may be loaded into the system from other sources. Forinstance, temperature and rain volume could be obtained and loaded,either automatically or manually, from a weather service.

By way of example, some embodiments may regulate the DO concentration ata desired level during the aeration process as explained above. In someembodiments, control panel 118 may store historical data, such as thevalve position regulating air flow that was used in previous treatmentprocesses to maintain the DO concentration at the desired level. Then,in subsequent treatment process, the previously-used valve position maybe applied as a default value to maintain the DO concentration at thedesired level. At the same time, in some embodiments dynamic monitoringand adjustment may continue so that the valve position is adjusted ifthe desired level is not maintained based on the default value. However,by using the default value based on historical data, some embodiments ofthe present invention may employ predictive analysis based uponhistorical data. In yet other embodiments, other historical data couldbe considered, such as valve positions used for similar concentrationsor other factors discussed above. Similarly, predictive analysis may beused based upon historical data concerning treatment process settingswith respect to other references, such as time of day, rain volume,suspended solid concentration, and influent flow rate and volume.Similarly, temperature may affect the rate of a treatment process, andtemperature values may be monitored and stored for past treatmentprocesses and may be used for predictive treatment analysis issubsequent treatments.

Other applications of wastewater treatment and applications unrelated towastewater treatment are also within the scope the present invention. Byway of example, embodiments of the present invention could includetreatments in oxidation ditches, sludge treatment, other wastewatertreatment processes, water storage, chemical storage, sequencing batchreactors, and pumping stations.

For instance, embodiments of the present invention may be used in sludgetreatment processes. Sludge is generally described as settlable materialthat is removed from wastewater, including, for instance, sediment,inert matter, and biological matter. Primary sludge is settlablematerial removed from influent wastewater prior to the wastewater beingtreated, and secondary sludge is settlable material removed afterwastewater treatment processes have been performed. Aeration is used insome sludge treatment processes and, in some embodiments of the presentinvention, control panel 118 can activate and/or deactivate aerationand/or mixing in sludge treatment processes as well as control theaeration rate and/or mixing rate. In some embodiments, the aerationand/or mixing time can be controlled by control panel 118 usingpredictive analysis based upon previous sludge treatments. In otherembodiments, aeration and/or mixing during sludge treatments can bebased, in whole or in part, upon the measured amount of suspended solidsin the sludge. For instance, increased mixing and/or aeration may beinitiated by control panel 118 for sludge having higher levels ofsuspended solids.

In some wastewater treatment systems, some sludge may be disposed ofwhereas other sludge (usually some portion of secondary sludge) may bereturned to the wastewater treatment tanks so that microorganisms in thesludge can digest waste in the influent wastewater. The sludge returnedto the wastewater treatment tanks is termed return activated sludge(RAS) and the disposed sludge is termed waste activated sludge (WAS).

The amount of RAS may be monitored and tracked. In some embodiments ofthe present invention, the amount of RAS may be a measured parameter forcontrolling aeration and/or mixing during wastewater treatmentprocesses. For instance, if higher amounts of RAS are introduced intobasin 2, control panel 118 may signal that increased mixing and/oraeration is necessary. In some embodiments, the measured value ofsuspended solids in the wastewater may be a factor for controllingaeration and/or mixing of the wastewater. By way of example, controlpanel 118 may signal for increased mixing if a high level of suspendedsolids is measured.

Other embodiments of the present invention may also indicate the amountof R.A.S. to introduce into basin 2 based upon real-time data and/orhistorical analysis. For instance, if weather conditions such asexcessive rain result in diluted influent wastewater, then less R.A.S.may be required and control panel 118 may indicate that less R.A.S. bereturned to the system. In some embodiments, the level of suspendedsolids in influent wastewater can be measured. If the BOD level is high,control panel 118 may indicate that additional RAS be provided to basin2. In yet other embodiments, historical data may indicate that theinfluent has increased suspended solids that peak times, such as duringmornings when people are preparing for school and work, and controlpanel 118 may indicate that additional R.A.S. be provided during thosetimes based upon historical data.

The foregoing description of illustrative embodiments of the inventionhas been presented only for the purpose of illustration and descriptionand is not intended to be exhaustive or to limit the invention to theprecise forms disclosed. Numerous modifications and adaptations thereofwill be apparent to those of ordinary skill in the art without departingfrom the scope of the present invention.

It will be understood that each of the elements described above, or twoor more together, may also find utility in applications differing fromthe types described. While the invention has been illustrated anddescribed in the general context wastewater treatment, it is notintended to be limited to the details shown, since various modificationsand substitutions can be made without departing in any way from thespirit and scope of the present invention. As such, furthermodifications and equivalents of the invention herein disclosed mayoccur to persons skilled in the art using no more than routineexperimentation, and all such modifications and equivalents are believedto be within the spirit and scope of the invention as described herein.

We claim:
 1. A system for automatically controlling a mixing processbased upon at least one dynamically-measured parameter, comprising: aprobe for dynamically measuring at least one parameter of a substance, acontrol panel in communication with the probe, wherein the control panelreceives data from the probe representing the measurement of the atleast one parameter, a programmable logic controller in communicationwith the control panel, and a mixer in communication with the controlpanel, wherein the system is configured to activate the mixer uponmeasurement of a first mixing parameter characteristic of adynamically-measured parameter and to deactivate the mixer uponmeasurement of a second mixing parameter characteristic of adynamically-measured parameter.
 2. The system of claim 1 wherein thesubstance is wastewater that is stored in a containment unit.
 3. Thesystem of claim 1 wherein the mixer comprises a nozzle in connectionwith a source of pressurized gas, wherein the nozzle comprises a fluidpassage having a plurality of outlets, and wherein the fluid passage isconfigured to release pressurized gas from the outlets in intermittentbursts to mix the wastewater.
 4. The system of claim 1 furthercomprising at least one secondary first mixing parameter characteristicand at least one secondary second mixing parameter characteristic,wherein in response to detection or calculation of the secondary firstmixing parameter characteristic the mixer is activated, and wherein, inresponse to detection or calculation of a secondary mixing parametercharacteristic, the mixer is deactivated.
 5. The system of claim 1further comprising a second probe for dynamically measuring at least onesecond parameter of the substance.
 6. The system of claim 2 wherein thedynamically-measured parameters measured by the probe and the system'shistorical cycle data are stored by the control panel.
 7. A method forcontrolling the mixing of a substance based upon dynamically-measureddata, the method comprising the steps of: measuring at least oneparameter of the substance; activating mixing of the substance uponmeasurement of a first mixing parameter characteristic of a measuredparameter; and deactivating mixing of the substance upon measurement ofa second mixing parameter characteristic of a measured parameter.
 8. Themethod of claim 7 wherein the substance that is stored in a containmentunit is wastewater.
 9. The method of claim 8 further comprisingactivating mixing of the wastewater in response to detection of asecondary first mixing parameter characteristic of a measured parameterinstead of in response to the first mixing parameter characteristic ifthe secondary first mixing parameter characteristic is detected beforethe first mixing parameter characteristic and deactivating mixing of thewastewater in response to detection of a secondary second mixingparameter characteristic of a measured parameter instead of the secondmixing parameter characteristic if the secondary second mixing parametercharacteristic is detected before the second mixing parametercharacteristic.
 10. The method of claim 8 further comprising storinghistorical data concerning treatment cycles, wherein the historical datacomprises at least some measured parameters.
 11. The method of claim 10further comprising utilizing the historical data to perform predictiveanalysis for a treatment process.